Figure 5.

p38 MAPK phosphorylates GR at S203 residues in vitro. Protein phosphorylation was performed as described in Materials and Methods. Top: Immunoprecipitated GR was incubated with assay buffer alone in the presence or absence of active p38 MAPK or calf intestine alkaline phosphatase. An ATP/Mg⁺⁺ cocktail was added to all samples except the buffer control. Proteins were extracted and assayed for GR-S203, GR-S211, GR-S226, and total GR by immunoblot analysis. Data are representative of three separate experiments. Bottom: Scanning densitometry of three representative GR-S203 immunoblots with each condition normalized over the area density of the corresponding GR content. The results are expressed as the fold increase over basal values. *P < 0.05 compared with untreated cells.